Consolidated Statements of Financial Position (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Accumulated depreciation	$ 5,066	$ 4,831
Long-term Debt, current portion	$ 867	$ 12
Preferred Stock, par value	$ 1	$ 1
Preferred Stock, shares authorized	10,000,000	10,000,000
Preferred Stock, shares issued	0	0
Preferred Stock, shares outstanding	0	0
Common stock, par value	$ 1	$ 1
Common stock, shares authorized	800,000,000	800,000,000
Common stock, shares issued	174,085,619	175,068,263
Common stock, shares outstanding	174,085,619	175,068,263